1. Field of the Disclosure
The present disclosure relates to an optical scanning apparatus and an image forming apparatus. The present invention particularly relates to an optical scanning apparatus including a shutter member provided to open and close an emission portion through which a light beam passes, and an image forming apparatus including the optical scanning apparatus.
2. Description of the Related Art
In an image forming apparatus using an electrophotographic technology, such as a copying machine and a laser beam printer, a light beam emitted from an optical scanning apparatus passes through components, such as a rotating polygon mirror (a polygon mirror), a scanning lens, and a reflection mirror. The light beam is then condensed in a spot shape, on a photosensitive drum surface that is charged electrically. At this moment, an electric potential on the photosensitive drum surface changes according to intensity of the light beam, and then toner from a developing unit adheres to the photosensitive drum surface based on a latent image. A transfer unit then transfers the toner on the photosensitive drum surface to a recording medium, such as a sheet of paper. The recording medium then goes through a fixing process, so that an image is formed on the recording medium, which is then discharged to the outside of the image forming apparatus. In the image forming apparatus, dust, toner and the like (hereinafter referred to as “dust and the like”) may settle on a transparent member covering the opening portion through which the light beam passes of the optical scanning apparatus. When the dust and the like settle on the transparent member, the light beam emitted from the optical scanning apparatus is partially blocked. As a result, the photosensitive drum surface is not appropriately irradiated with the light beam, thereby leading to such a problem that an image defect occurs. To address such a problem, Japanese Patent Application Laid-Open No. 2009-151111, for example, discusses an image forming apparatus including an optical scanning apparatus that has a shutter member and a cleaning member for the transparent member.
The optical scanning apparatus discussed in Japanese Patent Application Laid-Open No. 2009-151111 has a housing that houses optical components for exposure of photosensitive bodies. The housing has an emission window 212 for emitting a light beam, as illustrated in FIG. 6A. On a top surface of the housing, a slidable shutter 216 is provided with an opening 219. The image forming apparatus of Japanese Patent Application Laid-Open No. 2009-151111 further has a guide rail not illustrated. The guide rail guides a cleaning brush 215 having a brush portion 231, so that the cleaning brush 215 can move in a longitudinal direction of the emission window 212. When the cleaning brush 215 is moved towards the back side of the image forming apparatus (as indicated by a thin arrow illustrated in FIG. 6B) along the guide rail, the cleaning brush 215 comes in contact with a slant portion 213b of a rib. The shutter 216 then moves in a white arrow direction in FIG. 6B, to align the opening portion 219 and the emission window 212 with each other. In such a state that the cleaning brush 215 is in contact with a longitudinal extending portion 213a, the emission window 212 is exposed and therefore, the cleaning brush 215 can clean the emission window 212. In this way, when emission of a light beam from the optical scanning apparatus is not necessary, the shutter 216 covers the emission window 212 (See FIG. 6A), and the cleaning brush 215 removes dust and the like, when cleaning the emission window 212 (See FIG. 6B).
However, in the optical scanning apparatus discussed in Japanese Patent Application Laid-Open No. 2009-151111, when the cleaning brush 215 performs cleaning on the emission window 212, extra space in a height direction of the image forming apparatus is necessary by the thickness of the shutter 216 and the thickness of the cleaning brush 215. This may hamper downsizing of the apparatus, in the configuration of the optical scanning apparatus discussed in Japanese Patent Application Laid-Open No. 2009-151111. Moreover, due to a level difference between the shutter 216 and the emission window 212, the cleaned dust may resettle on an apparatus-front side of the emission window 212. For instance, as illustrated in FIG. 6C, the cleaning brush 215 in the optical scanning apparatus operates as follows in a conventional example. In the conventional example, there is a level difference “a” between the emission window 212 that is the emission portion for the light beam and the top surface of the shutter 216. Therefore, when being inserted from outside the image forming apparatus in a cleaning member inserting/removing direction, the cleaning brush 215 needs to be at a position that is higher than the emission window 212 by the level difference “a”. In this way, when it is necessary to clean the emission window 212, space is necessary by the level difference “a” and a thickness “b” of the cleaning brush 215. Therefore, the height of the image forming apparatus increases accordingly. Further, as illustrated in FIG. 6D, the cleaning brush 215 is removed from the image forming apparatus as follows in the conventional example. As illustrated in FIG. 6D, when the cleaning brush 215 is removed from the image forming apparatus after cleaning dust on the emission window 212, the brush portion 231 of the cleaning brush 215 may be caught in the shutter 216 due to the level difference “a”. This may cause the cleaned dust to fall in a corner portion “D” formed by the emission window 212 and the shutter 216, which may lead to occurrence of an image defect.
Aspects of the present invention are generally directed to a technique for removing dust on a transparent member of an optical scanning apparatus, while achieving downsizing of an apparatus.